2” all the way will be just fine.
On a old school gasser, changing the pipe size only changes the noise. Smaller pipe is much more snappy sound. larger pipe is deeper growl.
In college I had a 429 with 2" all the way. Very cackley.
Another thought on this. I have always thought the H or X pipe made the SB sound worse. My 95 Impala SS was a true dual exhaust from the factory. NO X or H. Once I removed the muffler but kept the small resonator it was the best sounding engine I has heard in a long time. I can't speak to the weird cross over intake putting more into one side or the other, but I do think H's and X's take away from the unique traditional sound.
